The invention pertains to composite panels and engineered products made of Arundo donax (a type of grass), and pulp and paper produced from Arundo donax.
There are several well-known technologies for producing particle board, using wood chips and other wood processing waste products. Indeed, these wood-based composite boards have found wide application particularly in building construction and the manufacture of furniture. More recently, the industry has produced oriented strand board (OSB) as a useful construction material. Both particle board and OSB fall into the category of xe2x80x9ccompositesxe2x80x9d because both contain a filler (wood fiber) embedded within a binder matrix. Another well-known wood composite is xe2x80x9cMDFxe2x80x9d (medium density fiber board). Other well known composite products are made with wood or other fibers using inorganic binders, such as cement, to make construction and decorative products.
The popularity of wood-based composites is based in large part on the availability of relatively low cost wood byproducts (chips, sawdust, etc.) that can be used in the composites. Indeed, many of the industry standards for the physical performance of these composites are based on wood-based composites. Since the manufacturing parameters for wood-based composites are well-known, and can often be customized for certain applications, there has been little incentive to investigate other fillers.
With the increasing demand for paper prepared from wood pulp, as well as worldwide demand for wood-based composites (which can substitute for lumber), there is now a perceived growing need for a substitute raw material for wood. While the supply of wood for use in these products is xe2x80x9crenewable,xe2x80x9d it requires setting aside land for long periods of time for tree farming. Moreover, when demand outstrips supply, because supply is based on forecasts of decades before when trees were planted, then a shortage inevitably develops. Since the wood required for these uses results in cutting millions of acres of forest each year, such shortages lead to serious worldwide concerns about large scale deforestation and its contribution to global warming.
There is yet a need for a material that can be readily substituted for wood in wood-based composites, and that can also be used to produce paper pulp for the fabrication of paper products. Extensive research had been conducted and production trials have been made in an effort to find a suitable non-wood fiber for composites and pulp but, until now, this work has met with very little success due to inferior properties, excessive costs and many commercial production drawbacks.
In one aspect of the invention, Arundo donax particles are provided. The particles, including chips and flakes, can be advantageously formed into pulp from which paper and paper products can be made. The particles can also be used in the production of particle boards.
In another aspect, the invention provides composites that include a binder matrix filled with Arundo donax particulates. In accordance with the invention, these composite boards use significantly less binder than wood-based composites, and exceed several of the physical properties of comparable wood-based composites, as measured by standards used in the industry.
The composites of the invention are produced by selecting nalgrass (a common name for Arundo donax), which is widely distributed as a native wild grass in many parts of the world. The nalgrass is charged to a flaker which contains sharp internal knife edges to reduce the nalgrass to small shards (e.g., flakes), which can then be charged to a hammermill for further size reduction. The resulting material is called a xe2x80x9cfurnish.xe2x80x9d The hammermill furnish is sized, preferably into at least two fractions. Each of the two fractions of nalgrass particulates is separately combined with a proportion of a resin. A layered structure, having alternate layers of fine and coarse nalgrass-resin mixture is then produced. The layered structure is subjected to heat and pressure for consolidation into a composite product. Satisfactory products may be made with a single layer, two layers, or more. Many commercial operations blend a variety of wood sources, such as hardwoods, softwoods, and recycled wood waste, in the manufacture of composites. Those skilled in the field will seek the advantages of nalgrass by blending into their furnish a portion of nalgrass with their available wood sources.
The invention also provides paper pulp, and paper products made from nalgrass. The raw pulp produced from the nalgrass is of lighter color than the pulp produced from woods that are typically used in paper production. Accordingly, a smaller amount of chemical bleach must be added to bleach the pulp to a desired whiteness. Nalgrass pulp is also stronger than most common hardwoods, such as aspen. The pulp of the present invention can also be utilized in other cellulose-based products including building products and modified cellulosic fibers such as viscose (e.g., rayon).